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1.
Int J Biol Macromol ; : 133936, 2024 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-39032908

RESUMEN

Palladium ion (Pd2+) plays an important role in our daily life, but poses a great threat to the environment and human health. Thus, it is desirable to exploit a rapid and sensitive approach to realize the detection of Pd2+. In this study, a cellulose acetate-based macromolecular fluorescent probe CA-NA-PA was successfully prepared for tracking amounts of Pd2+. CA-NA-PA showed an obvious "on-off" fluorescence response to Pd2+, accompanied by the fluorescence color changed from bright yellow to colorless. CA-NA-PA had some outstanding detection performances such as low detection limit (26 nM), extremely short response time (1 min), good selectivity and anti-interference ability. Based on the advantages of probe mentioned above, CA-NA-PA could realize recognition of Pd2+ concentration in environmental water and soil samples. What's more, the probe CA-NA-PA was applied to image Pd2+ in zebrafish as well as in live onion tissue due to the good biocompatibility and cell membrane permeability of cellulose, suggesting its wide application prospect in biosystems.

3.
Metabolism ; 155: 155911, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38609037

RESUMEN

BACKGROUND: The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing year by year and has become one of the leading causes of end-stage liver disease worldwide. Triggering Receptor Expressed on Myeloid Cells 2 (Trem2) has been confirmed to play an essential role in the progression of MASLD, but its specific mechanism still needs to be clarified. This study aims to explore the role and mechanism of Trem2 in MASLD. METHODS: Human liver tissues were obtained from patients with MASLD and controls. Myeloid-specific knockout mice (Trem2mKO) and myeloid-specific overexpression mice (Trem2TdT) were fed a high-fat diet, either AMLN or CDAHFD, to establish the MASLD model. Relevant signaling molecules were assessed through lipidomics and RNA-seq analyses after that. RESULTS: Trem2 is upregulated in human MASLD/MASH-associated macrophages and is associated with hepatic steatosis and inflammation progression. Hepatic steatosis and inflammatory responses are exacerbated with the knockout of myeloid Trem2 in MASLD mice, while mice overexpressing Trem2 exhibit the opposite phenomenon. Mechanistically, Trem2mKO can aggravate macrophage pyroptosis through the PI3K/AKT signaling pathway and amplify the resulting inflammatory response. At the same time, Trem2 promotes the inflammation resolution phenotype transformation of macrophages through TGFß1, thereby promoting tissue repair. CONCLUSIONS: Myeloid Trem2 ameliorates the progression of Metabolic dysfunction-associated steatotic liver disease by regulating macrophage pyroptosis and inflammation resolution. We believe targeting myeloid Trem2 could represent a potential avenue for treating MASLD.


Asunto(s)
Progresión de la Enfermedad , Hígado Graso , Inflamación , Macrófagos , Glicoproteínas de Membrana , Piroptosis , Receptores Inmunológicos , Animales , Humanos , Masculino , Ratones , Hígado Graso/metabolismo , Hígado Graso/patología , Hígado Graso/genética , Inflamación/metabolismo , Inflamación/patología , Hígado/metabolismo , Hígado/patología , Macrófagos/metabolismo , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/genética , Enfermedades Metabólicas/metabolismo , Enfermedades Metabólicas/patología , Enfermedades Metabólicas/genética , Ratones Endogámicos C57BL , Ratones Noqueados , Piroptosis/fisiología , Receptores Inmunológicos/metabolismo , Receptores Inmunológicos/genética
4.
Sci Adv ; 10(17): eadk5128, 2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38669333

RESUMEN

Cellular zinc (Zn2+) homeostasis is essential to human health and is under tight regulations. Human zinc transporter 1 (hZnT1) is a plasma membrane-localized Zn2+ exporter belonging to the ZnT family, and its functional aberration is associated with multiple diseases. Here, we show that hZnT1 works as a Zn2+/Ca2+ exchanger. We determine the structure of hZnT1 using cryo-electron microscopy (cryo-EM) single particle analysis. hZnT1 adopts a homodimeric structure, and each subunit contains a transmembrane domain consisting of six transmembrane segments, a cytosolic domain, and an extracellular domain. The transmembrane region displays an outward-facing conformation. On the basis of structural and functional analysis, we propose a model for the hZnT1-mediated Zn2+/Ca2+ exchange. Together, these results facilitate our understanding of the biological functions of hZnT1 and provide a basis for further investigations of the ZnT family transporters.


Asunto(s)
Calcio , Proteínas de Transporte de Catión , Microscopía por Crioelectrón , Zinc , Zinc/metabolismo , Zinc/química , Humanos , Proteínas de Transporte de Catión/metabolismo , Proteínas de Transporte de Catión/química , Calcio/metabolismo , Modelos Moleculares , Conformación Proteica , Dominios Proteicos , Transporte Biológico , Multimerización de Proteína , Células HEK293
5.
Int J Biol Macromol ; 266(Pt 1): 131209, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38565364

RESUMEN

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6-9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.


Asunto(s)
Celulosa , Flavonoles , Colorantes Fluorescentes , Mercurio , Mercurio/análisis , Celulosa/química , Celulosa/análogos & derivados , Colorantes Fluorescentes/química , Flavonoles/química , Flavonoles/análisis , Espectrometría de Fluorescencia/métodos , Límite de Detección , Concentración de Iones de Hidrógeno , Contaminantes Químicos del Agua/análisis , Cebollas/química , Imagen Óptica/métodos
6.
ACS Nano ; 18(16): 10758-10767, 2024 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-38598699

RESUMEN

Neural networks are increasingly used to solve optimization problems in various fields, including operations research, design automation, and gene sequencing. However, these networks face challenges due to the nondeterministic polynomial time (NP)-hard issue, which results in exponentially increasing computational complexity as the problem size grows. Conventional digital hardware struggles with the von Neumann bottleneck, the slowdown of Moore's law, and the complexity arising from heterogeneous system design. Two-dimensional (2D) memristors offer a potential solution to these hardware challenges, with their in-memory computing, decent scalability, and rich dynamic behaviors. In this study, we explore the use of nonvolatile 2D memristors to emulate synapses in a discrete-time Hopfield neural network, enabling the network to solve continuous optimization problems, like finding the minimum value of a quadratic polynomial, and tackle combinatorial optimization problems like Max-Cut. Additionally, we coupled volatile memristor-based oscillators with nonvolatile memristor synapses to create an oscillatory neural network-based Ising machine, a continuous-time analog dynamic system capable of solving combinatorial optimization problems including Max-Cut and map coloring through phase synchronization. Our findings demonstrate that 2D memristors have the potential to significantly enhance the efficiency, compactness, and homogeneity of integrated Ising machines, which is useful for future advances in neural networks for optimization problems.

7.
Science ; 383(6689): eadj4591, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38513023

RESUMEN

Brassinosteroids are steroidal phytohormones that regulate plant development and physiology, including adaptation to environmental stresses. Brassinosteroids are synthesized in the cell interior but bind receptors at the cell surface, necessitating a yet to be identified export mechanism. Here, we show that a member of the ATP-binding cassette (ABC) transporter superfamily, ABCB19, functions as a brassinosteroid exporter. We present its structure in both the substrate-unbound and the brassinosteroid-bound states. Bioactive brassinosteroids are potent activators of ABCB19 ATP hydrolysis activity, and transport assays showed that ABCB19 transports brassinosteroids. In Arabidopsis thaliana, ABCB19 and its close homolog, ABCB1, positively regulate brassinosteroid responses. Our results uncover an elusive export mechanism for bioactive brassinosteroids that is tightly coordinated with brassinosteroid signaling.


Asunto(s)
Transportadoras de Casetes de Unión a ATP , Proteínas de Arabidopsis , Arabidopsis , Brasinoesteroides , Adenosina Trifosfato/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transportadoras de Casetes de Unión a ATP/química , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Brasinoesteroides/metabolismo , Ácidos Indolacéticos/metabolismo , Conformación Proteica
8.
Immunity ; 57(4): 876-889.e11, 2024 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-38479384

RESUMEN

Concentrations of the secondary bile acid, deoxycholic acid (DCA), are aberrantly elevated in colorectal cancer (CRC) patients, but the consequences remain poorly understood. Here, we screened a library of gut microbiota-derived metabolites and identified DCA as a negative regulator for CD8+ T cell effector function. Mechanistically, DCA suppressed CD8+ T cell responses by targeting plasma membrane Ca2+ ATPase (PMCA) to inhibit Ca2+-nuclear factor of activated T cells (NFAT)2 signaling. In CRC patients, CD8+ T cell effector function negatively correlated with both DCA concentration and expression of a bacterial DCA biosynthetic gene. Bacteria harboring DCA biosynthetic genes suppressed CD8+ T cells effector function and promoted tumor growth in mice. This effect was abolished by disrupting bile acid metabolism via bile acid chelation, genetic ablation of bacterial DCA biosynthetic pathway, or specific bacteriophage. Our study demonstrated causation between microbial DCA metabolism and anti-tumor CD8+ T cell response in CRC, suggesting potential directions for anti-tumor therapy.


Asunto(s)
Neoplasias Colorrectales , Microbioma Gastrointestinal , Humanos , Ratones , Animales , Ácidos y Sales Biliares , Ácido Desoxicólico/farmacología , Linfocitos T CD8-positivos
9.
Nano Lett ; 24(3): 975-982, 2024 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-38189647

RESUMEN

Ferroelectric memristors hold immense promise for advanced memory and neuromorphic computing. However, they face limitations due to low readout current density in conventional designs with low-conductive ferroelectric channels, especially at the nanoscale. Here, we report a ferroelectric-mediated memristor utilizing a 2D MoS2 nanoribbon channel with an ultrascaled cross-sectional area of <1000 nm2, defined by a ferroelectric BaTiO3 nanoribbon stacked on top. Strikingly, the Schottky barrier at the MoS2 contact can be effectively tuned by the charge transfers coupled with quasi-zero-dimensional polarization charges formed at the two ends of the nanoribbon, which results in distinctive resistance switching accompanied by multiple negative differential resistance showing the high-current density of >104 A/cm2. The associated space charges in BaTiO3 are minimized to ∼3.7% of the polarization charges, preserving nonvolatile polarization. This achievement establishes ferroelectric-mediated nanoscale semiconductor memristors with high readout current density as promising candidates for memory and highly energy-efficient in-memory computing applications.

10.
ACS Appl Mater Interfaces ; 15(40): 47661-47668, 2023 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-37783452

RESUMEN

Searching for new phase-change materials for memory and neuromorphic device applications and further understanding the phase transformation mechanism are attracting wide attention. Phase transformation from the amorphous phase to the crystal phase has been unraveled in iron telluride (FeTe) bulk film deposited by pulsed laser deposition, recently. However, the van der Waals-layered feature of FeTe in the crystal form was not noted, which will benefit the scaling of the memory devices and shine light on phase-change heterostructures or interfacial phase-change materials. Moreover, the demonstration of advanced memory or neuromorphic device applications is lacking. Here, we investigate the phase transformation of FeTe starting from mechanically exfoliated van der Waals layers from a bulk single crystal. Surficial amorphization is revealed at the surface layers of FeTe flakes after exfoliation under ambient conditions, which could be transformed back to the crystalline phase with laser irradiation or heating. The conductance drop of the flake devices near 400 K verifies the phase transformation electrically. Memristor behavior of the amorphous surface in FeTe has been further demonstrated, proving the reversibility of the phase transformation and shining light on the possible applications of neuromorphic devices.

11.
Nat Plants ; 9(10): 1697-1708, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37666962

RESUMEN

Abscisic acid (ABA) is a phytohormone essential to the regulation of numerous aspects of plant growth and development. The cellular level of ABA is critical to its signalling and is determined by its rate of biosynthesis, catabolism and the rates of ABA transport. ABCG25 in Arabidopsis thaliana has been identified to be an ABA exporter and play roles in regulating stomatal closure and seed germination. However, its ABA transport mechanism remains unknown. Here we report the structures of ABCG25 under different states using cryo-electron microscopy single particle analysis: the apo state and ABA-bound state of the wild-type ABCG25 and the ATP-bound state of the ATPase catalytic mutant. ABCG25 forms a homodimer. ABA binds to a cone-shaped, cytosolic-facing cavity formed in the middle of the transmembrane domains. Key residues in ABA binding are identified and verified by a cell-based ABA transport assay. ATP binding leads to closing of the nucleotide-binding domains of opposing monomers and conformational transitions of the transmembrane domains. Together, these results provide insights into the substrate recognition and transport mechanisms of ABCG25 in Arabidopsis, and facilitate our understanding of the ABA transport and signalling pathway in plants.


Asunto(s)
Transportadoras de Casetes de Unión a ATP , Proteínas de Arabidopsis , Arabidopsis , Ácido Abscísico/metabolismo , Adenosina Trifosfato/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Microscopía por Crioelectrón , Regulación de la Expresión Génica de las Plantas , Mutación , Transportadoras de Casetes de Unión a ATP/metabolismo
12.
Cardiovasc Diabetol ; 22(1): 219, 2023 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-37620823

RESUMEN

BACKGROUND: Clinical observations suggest a complex relationship between obesity and coronary artery disease (CAD). This study aimed to characterize the intermediate metabolism phenotypes among obese patients with CAD and without CAD. METHODS: Sixty-two participants who consecutively underwent coronary angiography were enrolled in the discovery cohort. Transcriptional and untargeted metabolomics analyses were carried out to screen for key molecular changes between obese patients with CAD (CAD obese), without CAD (Non-CAD obese), and Non-CAD leans. A targeted GC-MS metabolomics approach was used to further identify differentially expressed metabolites in the validation cohorts. Regression and receiver operator curve analysis were performed to validate the risk model. RESULTS: We found common aberrantly expressed pathways both at the transcriptional and metabolomics levels. These pathways included cysteine and methionine metabolism and arginine and proline metabolism. Untargeted metabolomics revealed that S-adenosylhomocysteine (SAH), 3-hydroxybenzoic acid, 2-hydroxyhippuric acid, nicotinuric acid, and 2-arachidonoyl glycerol were significantly elevated in the CAD obese group compared to the other two groups. In the validation study, targeted cysteine and methionine metabolomics analyses showed that homocysteine (Hcy), SAH, and choline were significantly increased in the CAD obese group compared with the Non-CAD obese group, while betaine, 5-methylpropanedioic acid, S-adenosylmethionine, 4-PA, and vitamin B2 (VB2) showed no significant differences. Multivariate analyses showed that Hcy was an independent predictor of obesity with CAD (hazard ratio 1.7; 95%CI 1.2-2.6). The area under the curve based on the Hcy metabolomic (HCY-Mtb) index was 0.819, and up to 0.877 for the HCY-Mtb.index plus clinical variables. CONCLUSION: This is the first study to propose that obesity with hyperhomocysteinemia is a useful intermediate metabolism phenotype that could be used to identify obese patients at high risk for developing CAD.


Asunto(s)
Enfermedad de la Arteria Coronaria , Hiperhomocisteinemia , Obesidad , Humanos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/etiología , Enfermedad de la Arteria Coronaria/genética , Enfermedad de la Arteria Coronaria/metabolismo , Estudios Transversales , Cisteína , Pueblos del Este de Asia , Hiperhomocisteinemia/complicaciones , Hiperhomocisteinemia/genética , Hiperhomocisteinemia/metabolismo , Metabolómica , Obesidad/complicaciones , Obesidad/genética , Obesidad/metabolismo , Estudios Prospectivos , Factores de Riesgo , Transcriptoma , Angiografía Coronaria , Factores de Riesgo Cardiometabólico , Adulto , Persona de Mediana Edad , Anciano
13.
Plant Commun ; 4(6): 100632, 2023 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-37254481

RESUMEN

The phytohormone auxin plays central roles in many growth and developmental processes in plants. Development of chemical tools targeting the auxin pathway is useful for both plant biology and agriculture. Here we reveal that naproxen, a synthetic compound with anti-inflammatory activity in humans, acts as an auxin transport inhibitor targeting PIN-FORMED (PIN) transporters in plants. Physiological experiments indicate that exogenous naproxen treatment affects pleiotropic auxin-regulated developmental processes. Additional cellular and biochemical evidence indicates that naproxen suppresses auxin transport, specifically PIN-mediated auxin efflux. Moreover, biochemical and structural analyses confirm that naproxen binds directly to PIN1 protein via the same binding cavity as the indole-3-acetic acid substrate. Thus, by combining cellular, biochemical, and structural approaches, this study clearly establishes that naproxen is a PIN inhibitor and elucidates the underlying mechanisms. Further use of this compound may advance our understanding of the molecular mechanisms of PIN-mediated auxin transport and expand our toolkit in auxin biology and agriculture.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Humanos , Arabidopsis/metabolismo , Naproxeno/farmacología , Naproxeno/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Ácidos Indolacéticos/metabolismo , Plantas/metabolismo , Antiinflamatorios/farmacología , Antiinflamatorios/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismo
14.
Cell Discov ; 9(1): 36, 2023 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-37015924

RESUMEN

The transient receptor potential channel subfamily A member 1 (TRPA1) ion channel is an evolutionary conserved polymodal sensor responding to noxious temperature or chemical stimuli. Notably, the thermosensitivity of TRPA1 varies among different species or even different isoforms in the same species. However, the underlying molecular basis of its thermo-gating remains largely unknown. Here, we determine the structures of a heat-sensitive isoform of TRPA1 in Drosophila melanogaster in two distinct conformations with cryo-samples prepared at 8 °C. Large conformational changes are observed in the ankyrin repeat domain (ARD) and the coiled-coil domain between the two states. Remarkably, all 17 ankyrin repeats are mapped in the newly resolved conformation, forming a propeller-like architecture. Two intersubunit interfaces are identified in the amino (N)-terminal domain, and play vital roles during both heat and chemical activation as shown by electrophysiological analysis. With cryo-samples prepared at 35 °C, only one conformation is resolved, suggesting possible state transitions during heat responses. These findings provide a basis for further understanding how the ARD regulates channel functions, and insights into the gating mechanism of TRPA1.

15.
J Transl Med ; 21(1): 121, 2023 02 14.
Artículo en Inglés | MEDLINE | ID: mdl-36788538

RESUMEN

BACKGROUND: Liver metastasis is the leading cause of death in patients with colorectal cancer (CRC). Surgical resection of the liver metastases increases the incidence of long-term survival in patients with colorectal liver metastasis (CRLM). However, many patients experience CRLM recurrence after the initial liver resection. As an unavoidable pathophysiological process in liver surgery, liver ischemia-reperfusion (IR) injury increases the risk of tumor recurrence and metastasis. METHODS: Colorectal liver metastasis (CRLM) mouse models and mouse liver partial warm ischemia models were constructed. The levels of lipid peroxidation were detected in cells or tissues. Western Blot, qPCR, elisa, immunofluorescence, immunohistochemistry, scanning electron microscope, flow cytometry analysis were conducted to evaluate the changes of multiple signaling pathways during CRLM recurrence under liver ischemia-reperfusion (IR) background, including SGK1/IL-6/STAT3, neutrophil extracellular traps (NETs) formation, polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) infiltration. RESULTS: Hepatocyte serum/glucocorticoid regulated kinase 1 (SGK1) was activated in response to hepatic ischemia-reperfusion injury to pass hepatocyte STAT3 phosphorylation and serum amyloid A (SAA) hyperactivation signals in CRLM-IR mice, such regulation is dependent on SGK-activated IL-6 autocrine. Administration of the SGK1 inhibitor GSK-650394 further reduced ERK-related neutrophil extracellular traps (NETs) formation and polymorphonucler myeloid-derived suppressor cells (PMN-MDSC) infiltration compared with targeting hepatocyte SGK1 alone, thereby alleviating CRLM in the context of IR. CONCLUSIONS: Our study demonstrates that hepatocyte and immune cell SGK1 synergistically promote postoperative CRLM recurrence in response to hepatic IR stress, and identifies SGK1 as a translational target that may improve postoperative CRLM recurrence.


Asunto(s)
Neoplasias Colorrectales , Neoplasias Hepáticas , Proteínas Serina-Treonina Quinasas , Daño por Reperfusión , Animales , Ratones , Neoplasias Colorrectales/patología , Hepatocitos/patología , Interleucina-6/metabolismo , Isquemia/patología , Hígado/patología , Neoplasias Hepáticas/secundario , Recurrencia Local de Neoplasia/patología , Daño por Reperfusión/patología , Proteínas Serina-Treonina Quinasas/metabolismo
16.
Small Methods ; 6(11): e2200995, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36250994

RESUMEN

It is a major challenge to achieve a high-performance anode for sodium-ion batteries (SIBs) with high specific capacity, high rate capability, and cycling stability. Bismuth sulfide, which features a high theoretical specific capacity, tailorable morphology, and low cost, has been considered as a promising anode for SIBs. Nevertheless, due to a lack of direct atomistic observation, the detailed understanding of fundamental intercalation behavior and Bi2 S3 's (de)sodiation mechanisms remains unclear. Here, by employing in situ high-resolution transmission electron microscopy, consecutive electron diffraction coupled with theoretical calculations, it is not only for the first time identified that Bi2 S3 exhibits specific ionic transport pathways preferred to diffuse along the (110) direction instead of the (200) plane, but also tracks their real-time phase transformations (de)sodiation involving multi-step crystallographic tuning. The finite-element analysis further disclosed multi-reaction induced deformation and the relevant stress evolution originating from the combined effect of the mechanical and electrochemical interaction. These discoveries not only deepen the understanding of fundamental science about the microscopic reaction mechanism of metal chalcogenide anodes but also provide important implications for performance optimization.

17.
Cell Discov ; 8(1): 90, 2022 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-36085283

RESUMEN

In mitosis, accurate chromosome segregation depends on kinetochores that connect centromeric chromatin to spindle microtubules. The centromeres of budding yeast, which are relatively simple, are connected to individual microtubules via a kinetochore constitutive centromere associated network (CCAN). However, the complex centromeres of human chromosomes comprise millions of DNA base pairs and attach to multiple microtubules. Here, by use of cryo-electron microscopy and functional analyses, we reveal the molecular basis of how human CCAN interacts with duplex DNA and facilitates accurate chromosome segregation. The overall structure relates to the cooperative interactions and interdependency of the constituent sub-complexes of the CCAN. The duplex DNA is topologically entrapped by human CCAN. Further, CENP-N does not bind to the RG-loop of CENP-A but to DNA in the CCAN complex. The DNA binding activity is essential for CENP-LN localization to centromere and chromosome segregation during mitosis. Thus, these analyses provide new insights into mechanisms of action underlying kinetochore assembly and function in mitosis.

18.
Nat Commun ; 13(1): 5166, 2022 09 02.
Artículo en Inglés | MEDLINE | ID: mdl-36056043

RESUMEN

Gemin5 in the Survival Motor Neuron (SMN) complex serves as the RNA-binding protein to deliver small nuclear RNAs (snRNAs) to the small nuclear ribonucleoprotein Sm complex via its N-terminal WD40 domain. Additionally, the C-terminal region plays an important role in regulating RNA translation by directly binding to viral RNAs and cellular mRNAs. Here, we present the three-dimensional structure of the Gemin5 C-terminal region, which adopts a homodecamer architecture comprised of a dimer of pentamers. By structural analysis, mutagenesis, and RNA-binding assays, we find that the intact pentamer/decamer is critical for the Gemin5 C-terminal region to bind cognate RNA ligands and to regulate mRNA translation. The Gemin5 high-order architecture is assembled via pentamerization, allowing binding to RNA ligands in a coordinated manner. We propose a model depicting the regulatory role of Gemin5 in selective RNA binding and translation. Therefore, our work provides insights into the SMN complex-independent function of Gemin5.


Asunto(s)
ARN Nuclear Pequeño , Ribonucleoproteínas Nucleares Pequeñas , Ligandos , Unión Proteica , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Nuclear Pequeño/metabolismo , Ribonucleoproteínas Nucleares Pequeñas/metabolismo , Proteínas del Complejo SMN/metabolismo
19.
Nature ; 609(7927): 611-615, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35917925

RESUMEN

Polar auxin transport is unique to plants and coordinates their growth and development1,2. The PIN-FORMED (PIN) auxin transporters exhibit highly asymmetrical localizations at the plasma membrane and drive polar auxin transport3,4; however, their structures and transport mechanisms remain largely unknown. Here, we report three inward-facing conformation structures of Arabidopsis thaliana PIN1: the apo state, bound to the natural auxin indole-3-acetic acid (IAA), and in complex with the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). The transmembrane domain of PIN1 shares a conserved NhaA fold5. In the substrate-bound structure, IAA is coordinated by both hydrophobic stacking and hydrogen bonding. NPA competes with IAA for the same site at the intracellular pocket, but with a much higher affinity. These findings inform our understanding of the substrate recognition and transport mechanisms of PINs and set up a framework for future research on directional auxin transport, one of the most crucial processes underlying plant development.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Ácidos Indolacéticos , Proteínas de Transporte de Membrana , Apoproteínas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Enlace de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Ácidos Indolacéticos/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Ftalimidas/metabolismo , Conformación Proteica , Especificidad por Sustrato
20.
Mikrochim Acta ; 189(8): 285, 2022 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-35851426

RESUMEN

A large-size Bi2Se3 tape electrode (BTE) was prepared by peeling off a 2 × 1 × 0.5 cm high-quality single crystal. The feasibility of using the flexible BTE as an efficient bioplatform to load Au nanoparticles and probe DNA for HIV-1 DNA electrochemical sensing was explored. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) show that the resultant biosensor has a wide linear range from 0.1 fM to 1 pM, a low detection limit of 50 aM, excellent selectivity, reproducibility and stability, and is superior to the pM DNA detection level of Pt-Au, graphene-AuNPs hybrid biosensors. This outstanding performance is attributed to the intrinsic surface state of Bi2Se3 topological insulator in facilitating electron transfer. Therefore, BTE electrochemical biosensor platform has great potential in the application for sensitive detection of DNA biomarkers.


Asunto(s)
Técnicas Biosensibles , VIH-1 , Nanopartículas del Metal , Técnicas Biosensibles/métodos , ADN/química , ADN/genética , Electrodos , Oro/química , VIH-1/genética , Nanopartículas del Metal/química , Reproducibilidad de los Resultados
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